Circuit controlling device



May 18, 1937. T. J. MUDON CIRCUIT CONTROLLING DEVICE Filed Feb. 25, 1952 5 Sheets-Sheet l Z0 25 Z Z7 Z2 29 1'6 May 125 1937. T. J. MUDON 2,081,014

CIRCUIT CONTROLLING DEVICE Filed Feb. 25, 1932 3 Sheets-Sheet 2 May 18, 1937.

T. J. MUDON CIRCUIT CONTROLLING DEVICE Filed Feb. 25, 1952 5 Sheets-Sheet 3 Patented May 18, 1937 UNITED STATES PATENT OFFICE CIRCUIT CONTROLLING DEVICE Illinois Application February 25, 1932, Serial No. 595,077

1 Claim.

My invention relates to circuit controlling devices and more particularly to a device for controlling the making and breaking of high tension circuits receiving current from a low potential source through a transformer.

More specifically my device relates to a device for flashing on and off a plurality of gaseous conduction devices such for example as. the neon signs now so commonly used. It is well known that considerable difliculty has been encountered with these devices owing to the fact that the voltages used are of such high value on the secondary side of the transformer as to cause excessive arcing if the secondary circuit is opened.

It is the purpose of my invention to provide a flashing device of this character in which the gaseous conduction devices in a display may be successively energized and deenergized without opening the secondary which supplies the current operating them.

It is also a purpose of this invention to provide a device of this character in which the opening and closing of the main supply circuit occurs on the primary side of the transformer.

It is also a purpose of this invention to provide an improved method of flashing gaseous conduction devices whereby they may be consecutively or alternately illuminated and darkened in any desired order although all of them are fed from a common secondary transformer and the flashing is accomplished without either short circuit ing the secondary or opening the secondary circuit so long as it is energized.

Other and more specific objects of the invention will appear as the description proceeds when taken in connection with the accompanying drawings. It is to be understood, however, that the description and drawings are illustrative only and do not limit the invention to the exact details shown and described. It is obvious that many minor modifications may be made without departing from the scope of the invention.

In the drawings- Fig. 1 is a wiring diagram of an embodiment of my invention;

Fig. 2 is a cross section through the flashing mechanism used for double faced signs;

Fig. 3 is a side view of the mechanism shown in section in Fig. 2, certain portions thereof being broken away for the sake of clearness;

Fig. 4 is a detailed view of one of the timing cams used;

Fig. 5 is an end view of a modified form of circuit control; and

Fig. 6 is a side view of the mechanism shown in Fig. 5.

Referring now in detail to the drawings, I have shown schematically in Fig. 1 the devices necessary to carry out the system of flashing hereinbefore referred to. For example, in this figure I have provided a series of gaseous conduction tubes numbered I, 2, 3, 4, 5, 6, "I, and 8. The member 9 may also be in the form of the gaseous conduction tube on a suitable background and could be maintained steadily lighted if desired. The source of current supply is shown at III as leading to the transformer I I. This transformer is of the so-called constant current type, that is, it has built in with it a current limiting means which limits the output current of the secondary to-such a value as is safe to use on the gaseous conduction tubes. Transformers of the Constant current output type have a characteristic that the output voltage increases as the resistance across the output or secondary increases in order to maintain the current constant so that their open circuit voltage on the secondary is theoretically infinite. The result of opening the secondary circuit in a transformer of this type is usually to cause a break-down of the transformer, and for this reason it is of vital importance that the secondary of the transformer be always closed when the primary is closed. It is well known that tubes of this character have a negative resistance characteristic so it is necessary to provide some current limiting means in their source of supply. This transformer II is of the type having the secondary grounded at its mid point as indicated at I2, and, for total tubing lengths up to 30 feet or thereabouts, the secondary should deliver about 15,000 volts thus giving a voltage of 7,500 on each half of the secondary. On the primary side of the transformer II, I provide a circuit closing device indicated by the numeral I3. This circuit closing device has a stationary or yielding contact I4 and a movable contact I5, the details of which are shown more clearly in Figs. 2 and 3. One side of the secondary of the transformer is connected directly to tube I by conductor I6 and is also connected directly to contact 20 which is one of the movable contacts on the secondary side of the transformer. The other terminal of tube I is connected to one ter minal tube 2 and is also connected to stationary contacts I1 and I8 which are engaged by contact 20 in its raised and lowered positions, respectively. Contacts I1 and I8 are linked together by conductor I9.

The movable contacts 2|, 22, and 23 are respectively connected to the junctions between tubes I and 2, 2 and 3, and 3 and 4, are adapted to engage contacts in the raised and lowered positions which contacts are in all respects similar to contacts I! and I8. These contacts I have numbered 2429. The junction between tubes 4 and 6 is connected to a stationary contact which is adapted to be engaged by a movable contact 3i that is linked directly to another movable contact 32 and then to the return side of the secondary by a series of loops 33 and the conductor 34. The junction of tubes 5 and 6 connects to the stationary contact 35 opposite movable contact 32 and stationary contacts 36 and 37 are connected respectively to the junctions between tubes 6 and I and between tubes I and 8. Contacts 36 and 31 cooperate with the movable contacts 38 and 39. The free terminal of the tube 8 is connected by means of conductor 40 to the other side of the secondary.

The method of operation is briefly as follows: All of the movable contacts I5, 2823, 3I, 32, 38, and 39 are preferably moved in timed relation to each other, and the stopping position we will assume is with all of these contacts in raised position with the exception of contacts I5 and 2B. Thus a circuit is established through tube I over conductor I6 from one side of the secondary to contact 2|, and contact 2| being in raised position, as are all the succeeding contacts, the circuit is completed through these contacts to the conductor 34 and then to the other side of the secondary thus shorting out tubes 2-8 inclusive. Contact I5 is timed to close immediately upon contact 28 dropping away from its upper stationary contact. This closing energizes the secondary of transformer I I and lights up tube I which remains lighted owing to the interposition of a secondary cam 43 on its main timing cam 42 which is carried on the shaft 4|. The period of lighting tube I, however, may be cut off by using the lower contact I8 on which this contact engages in its lowered position, the only essential feature being to make the time drop of contact 29 suficiently long to enable contact 2| to move away from its upper contact 24.

Returning to the regular operation, while contact 20 is dropping between the stationary contacts II and I8, contact 2| moves away from contact 24 thus breaking the short circuit around tube 2 and putting the voltage across this tube so that it in turn also lights up. Then tubes 3 and 4 are successively lighted in the same fashion, their periods of lighting depending upon the time of drop of their contacts 2|, 22, and 23 from the upper to the lower stationary contacts. When tube 4 has been lighted, tube 5 next in line has its short circuit removed by contact 3I moving away from stationary contact 30 thus completing the circuit through tube 5, contact 35, contact 32, loops 33, and conductor 34. By properly arranging the time cams, tubes I-4 may all be extinguished by the time 5 lights up or any one or more of them may be maintained illuminated as desired. Tube 5, which as shown is the border tube, remains lighted while contacts 32, 38, and 39 drop away from their respective stationary contacts 35, 36, and 31 in order to light up the tubes 6, I, and 8. Thus tubes 5, 6, I, and 8 are consecutively flashed on, and, at the completion of a cycle, no break in the circuit has yet occurred.

Now in order to break the circuit without destructive arcing in the secondary, I merely time the mechanism so that contact I5 at this time separates from its contact I4 thus breaking the primary side of the transformer. It is obvious, of course, that the combinations of tubes and their order of flashing on and off as well as the periods of on and off may be properly governed by timing the cam mechanisms which operate the respective movable contacts.

The functions of the switch I3 and its contacts I4 and I5 is to darken the sign by turning off the current from the transformer. If the secondary of the transformer were used to darken the sign, that is to say if all the tubes were shorted across the secondary circuit or if the secondary circuit were broken, either a short circuit of the secondary or an open circuit of the secondary would result. Therefore, if the whole sign is to flash on and off in addition to the successive flashing of the tubes, I find the best way to accomplish this result is by means of the primary control switch I3. As hereinbefore stated, the arrangement is such that tube I is lighted by the closing of the primary switch I3, and the darkening of the sign after tubes 5, 6, l, and 8 have been illuminated in series is accomplished by opening the primary of switch I3.

Several distinct advantages are obtained by this system in addition to its flexibility as to timing and the number of tubes used. One of these is the fact that, when any of the secondary contacts are opened, it does not create an open circuit in the secondary and thus cause arcing. It merely removes a short circuit around a tube so that the maximum voltage across the contact at any time is comparatively low when contrasted with the total voltage across the secondary upon open circuit. It is a characteristic of constant current transformers of this type that they break down upon open circuit. The voltage tends to build up higher and higher as the secondary resistance increases. It is, therefore, highly important to maintain always a closed secondary circuit, and this device does that without hampering the flashing of the several tubes in the least.

Another distinct advantage lies in the fact that with the arrangement as shown it is never necessary to short circuit secondary although the tubes are controlled by short circuit connections around them. The timing of the opening of contacts I5, 25, 2i, 22, and 23, and particularly I5 and 22', determines whether or not there will be a short circuit. So long 28 opens before I5 closes and remains open until one of the other contacts of the series opens, no short circuit will be obtained provided the succeeding tubes are not short circuited out before some other tube is lighted.

Referring now to Figs. 2-4, I illustrate the preferred mechanism for operating such contacts as 2!), 21, etc. In this figure, the shaft M is mounted on a suitable standard 44 which in turn is mounted upon the base 45 of the flasher. Uprights 46 and ii support the frame 48 which in turn carries the stationary and movable contacts. The device shown in Fig. 2 is a double construction for operating two sides of a double face sign so that the movable contact mechanisms 49 and 56 are duplicates and are operated by a single cam 42 which engages with the roller 5I upon the bar 52 carrying pins 53 and 54 which in turn carry the movable contacts 55 and 56. An upright standard 5'! supports the stationary contacts 58 and 59 which contacts are yieldingly mounted in the cross bar 60 and normally held in the lowered position by springs GI and B2. The auxiliary contacts such as indicated at 63 are provided in order that contact 56 may establish contact in its lowered position. Contact 56 is connected directly through the secondary feed line while contact 59 leads to the next succeeding tube in each instance. Conductor 19, of course, links the upper and lower stationary contacts together. It is obvious, of course, that as many of the cams 42 may be used as is desired and their shape may be changed as well as the shape and relative position of the auxiliary cam 43 in order to get the proper timing. In Fig. 3, I have shown at the extreme left hand end the stationary contact 14 which is movable up and down in the frame to adjust the timing. This is accomplished by providing a sleeve 64 which is screw-threaded into the frame 60 and carries the yielding mechanism forcing down contact I4.

Referring now to Figs. 5 and 6,, in this form of the invention the drive shaft M is the same as before, and earns 42 and 43' are operated much the same as in the first form of the invention described. This cam, however, operates upon a rocker arm 65 which is mounted on a standard 66 and which carried at its free end the laterally running contact head 61. When operating to consecutively flash tubes on, as tubes 5, 6, l, and B are flashed in Fig. 1, the rocker arm contact 61 is merely linked by a flexible conductor to the next adjacent rocker arm contact on each side thereof, and this connection is to one side of the secondary of the transformer much in the manner of the flexible leads 33 in Fig. 1. In operat ing, the rocker arm is forced up against the contact 68 which is yieldingly mounted in order that it may move up with the contacts 61 for a period of time. When this method of operation is used for such contacts as 20, then two parallel push rods such as 68 must be used as indicated in Fig. 6, and contact 61 is elongated so as to form a bridging contact connecting the two parallel members 68. Suitable leads such as indicated at 69 connect the upper contacts 68 with the lower contacts 10 so that, when the bridging contact 61 drops to its lower position, it still shorts out its tube in the same manner as contact as in Fig. 1.

In experience I have found this system of flashing gaseous conduction devices to be reliable. As an example of the values found in operating the device in using tubes of three foot length or less in series and using a 15,000 volt transformer with the mid-point grounded, I find that with the first tube three feet long, the voltage at the transformer terminals was 10,170 volts. Upon the next change to include a second tube of three feet in length in series with the first, the transformer voltage jumped up to 11,585 volts, but the drop across the tube, whose short circuit was opened in order to put it on the line, measured only 1,415 volts. The next tube cut in was a two foot tube in the series, and the voltage across the transformer terminals jumped to 12,840. Upon measuring the drop across the third tube placed in series, I found it to be 1,255 volts. The fourth tube inserted was again a two foot tube, and the drop across it was 1,335 volts.

It is believed to be clear from these figures that, by the short circuiting method of bringing the tubes onto the line, I have a comparatively low voltage to break when I open such contacts as 20 to 23 and light the tubes. The secondary of the transformer is never opened at any time since the tubes are always across this circuit and are only cut out by short circuiting the current around them. The maximum voltage drop I obtained in cutting in any tube was less than 1,500 volts which, of course, does not cause excessive arcing on the short circuit terminals.

From the above description, it is believed that the construction and operation of this device will be clear to those skilled in this art.

Having thus described my invention, what I claim as new and desire to secure by Letters Patent is:

In a display system having a transformer provided with a primary winding and circuit therefor and a secondary winding and a series of more than two gaseous conduction tubes continuously connected across the secondary winding in series, means to individually flash said tubes without either short circuit or open circuit of the transformer secondary comprising a circuit closing device connected in parallel with each tube, said device adapted when closed to establish a short circuit across the terminals of the tube, and means to open and close said devices in a definite order to successively flash and darken the tubes, said means having at least one of said devices open at all times, and a circuit closer in said primary circuit actuated by said means to periodically entirely darken the system.

THOMAS J. MUDON. 

